function execl()
{
var name = document.getElementById("txtSelectUserID").value;
winOpen("inc/ExportExcel.aspx?id='" + name + "'");
}<asp:TextBox ID="txtSelectUserID" runat="server"></asp:TextBox>
{
var name = document.getElementById("txtSelectUserID").value;
winOpen("inc/ExportExcel.aspx?id='" + name + "'");
}<asp:TextBox ID="txtSelectUserID" runat="server"></asp:TextBox>
{
Button1.Attributes.Add("onClick", "execl()");
}